Method for securing cables in duct or pipe system

ABSTRACT

The invention concerns a method for securing cables or elongate hollow sections in duct or pipe systems for flowing media, and a cable network in a duct or pipe system. The cable or elongate hollow section to be laid is anchored by high-tensile-strength elements between anchoring points. The high-tensile-strength element may be a separate element or an element incorporated in the cable sheath or in the hollow section. Furthermore, the invention concerns the reduction of sags.

This is a divisional application of Ser. No. 09/266,528 filed Mar. 11,1999 now U.S. Pat. No. 6,377,734, the contents of which are herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

The invention relates to a method for securing cables in a duct or pipesystem for flowing media, such as gas, waste water, rain water or mixedwater.

German Gebrauchsmuster DE 297 00 912 has disclosed a fiber-optic cableused for this system is fixed using resilient securing elements, forexample, the fiber-optic cable being arranged between the wall and thesecuring element. Appropriate robots are required for the securing orfor the introduction of the securing elements in inaccessible duct orpipe systems, which robots, under remote control, set down the securingelements at appropriate distances and thus fix the introducedfiber-optic cable.

SUMMARY OF THE INVENTION

The first object of the invention is to provide a method which enablesthe laying of a cable or other elongate hollow section in a duct or pipesystem in a simple manner. This object is achieved with a methodcomprising the steps of providing a duct or pipe system with at leasttwo accessible locations, and either tensioning a cable with at leastone high-tension-strength element between two accessible locations ortensioning a high-tensile-strength element between the two accessiblelocations and then attaching the cable to the high-tension-strengthelement.

Furthermore, the invention is based upon a second object, which consistsin designing a cable network for a duct or pipe system which can beinstalled by the method according to the invention. The object isachieved by means of a cable net work comprising a duct or pipe systemhaving spaced anchoring points and a cable is either fixed to at leastone high-tensile-strength element which is attached by securing theelement to the anchoring points at appropriate distances or includes thehigh-tensile-strength element and is anchored in the system to thespaced anchoring points.

By comparison with the known prior art, the method according to theinvention and the cable network according to the invention affordconsiderable advantages, which are primarily manifested in simple andshort mounting, the means required for this purpose likewise beingsimple and extremely cost-effective. Further advantages may be seen inthe fact that in the method according to the invention, the duct or thepipe can hardly be blocked up by the introduced cable since there are nodeposit points for contaminants to be found within the duct or pipe. Themounting of a cable by anchoring is generally already known fromoverhead cable technology, so the aids which are essentially familiar inthat technology can also be employed in the context of mounting within aduct or pipe system. As is shown, however, there is a need for intensiveconsiderations to use such a laying system in a duct or pipe system,since only relatively complicated mounting methods have been used todate. Thus, in inaccessible duct or pipe systems, robot vehicles havebeen necessary to date in order to secure the subsequently insertedcables in such a way that they do not constitute an obstacle. It isadvantageous, moreover, that the method according to the invention canbe used for any type of ducts or pipes made of metal, stoneware orplastic, since the securing for a high-tensile-strength element isperformed in each case at the anchoring points which are each arrangedat the access locations of the duct or pipe network. It is alsoadvantageous that during duct repairs, for example, the cables or hollowsections can be removed from the duct with extremely little effort,thereby enabling the repair to be carried out without difficulties.Afterwards, the installation is just as simple as during the originallaying.

In the case of the method according to the invention, firstly, the cableor the hollow section is pulled in or pushed in. Afterwards, theanchoring points are secured on the shaft walls or shaft outlets of theduct or pipe system. In the simplest case, according to the invention, ahigh-tensile-strength element, for example a tension cable known per se,such as a steel cable, is suspended from the anchoring points andcorrespondingly anchored by means of a turnbuckle. Any desired cable orelongate hollow section can then be attached to such ahigh-tensile-strength element using suitable securing means, for exampleusing clamps or restraint coils. Since the high-tensile-strength elementwith the attached cable or hollow section is hung in each case in theupper region of the duct or pipe, it does not interfere with the flow ofthe flowing media, such as gas, waste water, rain water or mixed water,with the result that no deposits can form. In addition, it is stillpossible to use robots, without any obstructions, for example in orderto inspect the duct system. The possible anchoring length of such ahigh-tensile-strength element with attached cable or hollow sectiondepends in each case on the duct routing and the permissible anchoringforce of the high-tensile-strength element. In addition, thehigh-tensile-strength element can also be additionally fixed inintermediate shafts with the aid of supporting coils or deflectionrollers, thereby enabling longer anchoring lengths.

In the case of this method according to the invention, however, it isalso possible to use high-tensile-strength cables in whichhigh-tensile-strength elements are already incorporated in the cablestructure, in particular in the cable sheath, or in the hollow section,or are secured at the surface. The laying procedure is even simpler inthe case of this variant since the high-tensile-strength element alreadyforms a unit with the cable or hollow section, with the result that onlyone laying operation is required. At the anchoring points, thehigh-tensile-strength element is then respectively removed from thecable structure or the hollow section and fixed to the anchoring pointsfor anchoring purposes. Anchoring coils can also be wound onto therespective cable, which coils are then suspended from the respectiveanchoring point. A turnbuckle is then additionally interposed at theother end of the cable or hollow section, the requisite anchoringultimately being effected by the turnbuckle.

Depending on the method, it is possible to use any desired types ofcables for this kind of laying, such as microcables which comprise athin tube and optical waveguides loosely introduced therein. It is alsopossible to use dielectric cables, for example an “all dielectric selfsupportly cable” (ADSS) having a rodent-proof sheath or else a so-calledTOP cable, which is provided with a glass-fiber-reinforced plasticsheath over the cable core. Further types of cables are specified inconnection with the description of the Figures.

The present invention is furthermore based on the object or reducing thesag between two anchoring locations in the case of anchored cables orelongate hollow sections within a duct or pipe system. This object thathas been set is achieved with a method of the type explained in theintroduction by virtue of the fact that at least one contact-pressuremeans is inserted in the region between two anchoring points within theduct or pipe system, and that the high-tensile-strength element with anattached cable or a cable with at least one high-tensile-strengthelement or an elongate hollow section with at least onhigh-tensile-strength element is subsequently pressed against the innerwall of the duct or pipe system as a result of expansion of thecontact-pressure means.

As is already known, high-tensile-strength elements with an attachedcable, cables with at least one integrated high-tensile-strength elementor an elongate hollow section with a high-tensile-strength element aretensioned between entry shafts in duct or pipe systems. If there arevery long anchored lengths or if the course of the duct or pipe systemis not straight, an increased sag is possible in the central region,which sag means that problems may possibly occur during the customarycleaning processes or during duct operation. According to the invention,then, an expandable or spreadable contact-pressure means is introducedin the region of the largest sag, where it is finally expanded or spreadopen. As a result, the introduced high-tensile-strength element withattached cable, the cable with an integrated high-tensile-strengthelement or a hollow section with a high-tensile-strength element ispressed against the inner wall of the duct or pipe system, so that, bythis means, there is no longer any sag. As a result of the long anchoredlength being divided into two partial regions, the sag established inthe partial regions is considerably reduced, with the result that it isnot necessary to expect nay disruption in duct operation. Thecontact-pressure means that is used according to the invention is, forexample, a plastic hose which, if required, is reinforced with glassfibers and is generally referred to as a “part-liner”. This plastic hoseis preferably coated or impregnated with a curable adhesive, with theresult that it can be fixed on the inner wall of the duct or pipe systemafter being expanded or spread open. Such a part-liner is pushed, forexample, onto a rubber sac and, with the aid of a robot, is taken to theintended location, usually the middle of an anchored length. At thatpoint, the sac is inflated with air or a propellant gas with the resultthat the part-liner is pressed onto the inner wall, where it alreadysticks by virtue of the adhesive. Once the part-liner has been pressedonto the inner wall, the sac is moved again and, depending on the typeof adhesive, the adhesive is cured with the aid of UV or infraredirradiation or with hot air.

It is also possible to use contact-pressure means in the form ofspreadable or expandable rings made of plastic or steel, in particularstainless steel. Such contact-pressure means can be used separately bythemselves or else in connection with a hose-like part-liner if, forexample, the supporting force of the part-liner is to be reinforced. Insuch a case, firstly, the contact-pressure means in the form of the ringwill be installed by spreading or expansion and then the hose-likepart-liner will be mounted over it in the manner already described.Suitable adhesives for the part-liner are the materials which aregenerally suitable for such applications and must be, in particular,resistant to water and chemicals. Thus, the use of two-componentadhesives is also entirely possible.

Other advantages and features of the invention will be readily apparentfrom the following description of the preferred embodiments, thedrawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross sectional view of a cable networkaccording to the invention, in which a high-tensile-strength cable ispulled in and anchored;

FIG. 2 is a cross sectional view of a high-tensile-strength fiber-opticcable with high-tensile-strength elements incorporated therein;

FIG. 3 is a cross sectional view of an elongate hollow section withhigh-tensile-strength elements lying on the outside;

FIG. 4 is a cross sectional view of an oval hollow section withhigh-tensile-strength elements incorporated therein;

FIG. 5 is a cross sectional view of an elongate hollow section having around cross section;

FIG. 6 is a cross sectional view of the securing of a fiber-optic cableon a separate high-tensile-strength element;

FIG. 7 is a cross sectional view of a submarine microcable;

FIG. 8 is a cross sectional view of a high-tensile-strength overheadcable;

FIG. 9 is a cross sectional view of a TOP cable with aglass-fiber-reinforced plastic sheath;

FIG. 10 is a cross sectional view of an OWK cable with twohigh-tensile-strength elements situated oppositely in the cable sheath;

FIG. 11 is a cross sectional view showing two securing variants for theanchoring of high-tensile-strength elements;

FIG. 12 is a cross sectional view of a prior art system; and

FIG. 13 is a cross sectional view showing the use of a contact-pressuremeans according to the invention in the central region of an anchoredlength.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an anchored cable KB, which is pulled in and anchoredwithin a duct or pipe system K. In the case of this exemplaryembodiment, the cable KB is one which itself has high-tensile-strengthelements integrated in it. An anchoring zone extends generally from anaccessible duct inlet location KE1 to a second duct inlet location KE2,which are generally designed as entry shafts. Anchored on the walls ofthese duct inlet locations KE1 and KE2 are anchoring points ASP1 andASP2, respectively, to which at least one high-tensile-strength elementof the cable is secured, an anchoring coil AS or similar retainer beingarranged in each case at the exit location of the cable. At one end ofthe anchoring zone, this anchoring coils AS is attached directly to theanchoring point ASP2, while the second anchoring coils AS is suspendedby a turnbuckle SS. The turnbuckle SS is then suspended from theanchoring point ASP1 by its second end and serves to anchor the cable KBand the high-tensile-strength element incorporated therein, which is notillustrated here for the sake of clarity. The cable KB itself is thenrouted further, for example to a corresponding outlet, a serviceconnection or the like. A similar configuration is produced if aseparate high-tensile-strength element is anchored within the duct orpipe system K, in which case, however, the corresponding cable is thenattached with securing means, as illustrated in FIG. 6, for example. Inthis case, a high-tensile-strength cable is not necessary. In otherwords, any type of cable can be used when a separatehigh-tensile-strength element is used, as will be demonstrated later insubsequent drawings using examples. FIG. 1 clearly reveals that by andlarge the free space of the duct or pipe system remains free of securingunits for cables that have been required previously in the prior art.The duct or pipe system can be arranged in any desired foundation, forexample underneath a street section SP, the inlet and outlet locationsalso being utilized for leading the cables in and out. It is a majoradvantage, moreover, that a plurality of cables can be routed inparallel, it even being the case, under certain circumstances, that aplurality of cables can be routed in parallel, it even being the case,under certain circumstances, that the high-tensile-strength element canbe utilized for a plurality of cables. The same principles of theinvention apply when hollow sections with or withouthigh-tensile-strength elements are pulled in, so further sketches ordescriptions are unnecessary.

FIG. 2 shows a fiber-optic cable KB1, in which two longitudinalhigh-tensile-strength elements ZE are integrated in the cable sheath KMso that they are already situated oppositely. The cable core KScontains, for example, optical waveguides LWL or else copper conductorsor a combination of both. Consequently, this cable KB1 does not requirean additional high-tensile-strength element, since the anchoring can beperformed by means of the integrated high-tensile-strength elements ZE.

FIG. 3 shows that the laying method can also be utilized for elongatehollow sections HP1, in this case high-tensile-strength elements ZE1being arranged longitudinally in an adhering manner along the hollowsection HP1. The anchoring to the anchoring points is once againeffected by means of these high-tensile-strength elements ZE1.Electrical conductors, optical waveguides, optical-waveguide strips,electrical cables, dielectric cables or else, especially, microcablescan now subsequently be introduced as desired into the cavity H1 of thehollow section HP1.

FIG. 4 shows a planar or oval hollow section HP2, which, longitudinally,has a correspondingly shaped cavity H2 into which, once again, thecorresponding conductors or cables of any desired type can be pulled.The anchoring within the duct or pipe system is once again effected bymeans of two longitudinal integrated high-tensile-strength elements ZE2.

FIG. 5 shows a hollow section HP3 having a circular cross section intowhose longitudinal cavity H3 conductors or cables can be inserted asdesired. The anchoring is once again performed by means of thehigh-tensile-strength elements ZE3 embedded in the hollow section HP3.

FIG. 6 then shows the example for the laying of a cable which does nothave any high-tensile-strength elements, this example having beenindicated in the course of the description with reference to FIG. 1. Anydesired conductors, such as optical waveguides LWL in this exemplaryembodiment, for example, can be routed inside such a cable KB2. In thisexemplary embodiment, the anchoring within the duct or pipe system isthen effected not by means of elements of the cable KB2, but by means ofa separate high-tensile-strength element ZE4, which is gripped at theanchoring points and is anchored by means of a turnbuckle. The cable KB2is then attached to this anchored high-tensile-strength element ZE4 andfixed with the aid of securing means BE. Consequently, the simple methodaccording to the invention can also be used in the case of cables orelse in the case of hollow sections without high-tensile-strengthelements.

FIG. 7 shows in an example that it is also possible to use a submarinemicrocable. Maxibundles MB having optical fibers are contained insidethe microcable. The maxibundles may be composed of metal or of plastic.Arranged over them are stranded steel wires SD, which are used foranchoring to the anchoring points in the course of anchoring by themethod according to the invention. Extending over the wires SD is anouter sheath AM composed of polyethylene, for example.

FIG. 8 shows a so-called sheath-only cable, for example a “FIG. 8cable”. This involves a combination of any desired cable KB and a steelcable SS, which, situated one above the other, are surrounded by acommon plastic sheath KM, it also being possible for thehigh-tensile-strength element SS to extend in a recess AF in the cablesheath KM. In this case, the steel cable SS serves for anchoring withinthe duct or pipe system by the method according to the invention. Thecable that is used may also be, for example, a microcable, comprising atube and optical waveguides LWL loosely introduced therein. If ametallically-conducting tube is involved, this may, for example, beconcomitantly used as a current lead as well. Rodent-protected cablesare also especially suitable for use in a duct or pipe system.

FIG. 9 shows an optical overhead cable KB3 with a tubular supportingelement (TOP cable) which can likewise be laid and anchored by themethod according to the invention. This cable KB3 is anchored as awhole, since it contains a high-tensile-strength glass-fiber-reinforcedplastic sheath GFKM. Inside the latter, there is either a stranded cablecore VS or a maxibundle of optical waveguides. The entire system issurrounded by an outer sheath AM.

FIG. 10 additionally shows a so-called OWK cable, which has incorporatedin its outer sheath AM, situated oppositely, high-tensile-strengthelements in the form of steel wires SD. The core of this cable KB4contains a stranded cable core or a maxibundle MB of optical waveguides,surrounded by a rodent-proof grooved sheath NSRM.

In addition to these exemplary embodiments of cables mentioned, by andlarge further embodiments are suitable which, in principle, canwithstand the requirements with respect to the conditions prevailing ina duct and pipe system.

The anchoring points used for the high-tensile-strength elements may be,for example, hooks, ring eyes or similar securing elements, which arepegged or driven, for example, into the inlet or entry locations of theduct or pipe system. FIG. 11 shows two other variants for the securingof the high-tensile-strength elements, it being irrelevant whether therespective high-tensile-strength element is arranged in the cable orwhether an independent element is used. Thus, a spreading apparatus, forexample a spreading ring or clamping ring KR, can also be clamped in theentry location of the duct or pipe system by being spread open, so thatthe entry shaft is not damaged during the securing operation. Arrangedon this clamping ring KR is at least one retainer H, which projects intothe duct or the pipe in order to be able to ensure free anchoring of thehigh-tensile-strength element ZE. In the case of the anchoring variantin the right-hand part of FIG. 11, a cable KBR without anyhigh-tensile-strength elements is used, for example, with the resultthat a separate high-tensile-strength element ZE is anchored on theretainer H, to which element the cable KBR is attached. The cable KBR isdirected further into the inlet location KE.

The left-hand side of FIG. 11 shows a variant in which the cable KBL isrouted up by a deflection roller UR into the inlet location, where thehigh-tensile-strength element, for example of the cable, is then securedto the anchoring point by means of a tensioning unit SE.

In all of the exemplary embodiments according to the invention, it isalso possible for a plurality of anchoring units of cables and/orhigh-tensile-strength elements to be arranged so that they run parallel.When an electrically-conductive, separate, high-tensile-strength isused, this could be used as a current collector for robots which areused for service purposes.

In all of the exemplary embodiments according to the invention, it isalso possible for receptacles for excess cable and/or optical waveguidelengths to be arranged at the inlet locations, for example in theclamping rings, which are then provided with corresponding guides andretainers.

FIG. 12 shows a cable KB, which may be either a high-tensile-strengthelement with an attached cable, a cable with an integratedhigh-tensile-strength or a hollow section with a high-tensile-strengthelement, and the cable KB is anchored in a duct or pipe system K, forexample for gas, waste water, rain water or mixed water, between twoduct inlet locations KE1 and KE2. It is indicated in this case that thecable KB is fixed in the inlet locations KE1 and KE2 and is inserted viadeflection arches UB in each case into the duct or pipe system K andanchored. A sag with an arcuate profile known per se is ineluctablyproduced in this case, the largest sag DHO being established in thecenter in the case of free routing. This sag DHO can be disruptive fornormal duct or pipe system operation, since, for example, cleaningapparatuses may bump into it or refuse may accumulate to the point ofblockage.

FIG. 13 demonstrates the effect of the present invention and a solutionto the above problem. In order to avoid the interfering sag, acontact-pressure means is inserted at the duct or pipe system K in theregion of the large sag, which means presses the cable KB against theinner wall of the duct or pipe system. The consequence of this is thatthe originally large sag is divided into smaller sags DHM, which arethen each established in the center of the partitioned regions oranchored lengths. It may be assumed in this case that given the samecable KB, the same anchoring force and the same total anchored length,the sags DHM established in the partial regions amount to approximatelyonly ¼ of the original sag DHO when a contact-pressure means is arrangedcentrally in the total anchored length. To support the cable KB, forexample, a so-called part-liner PL is inserted and expanded, as hasalready been described above in the general part. In the case of longanchored lengths, it is also possible to implement a plurality ofsupports with part-liners PL or with the aid of expandable or spreadablerings. In this case, the number of such supports depends essentially onthe cable KB used, the anchoring force and the length of the totalanchored region, the contact-pressure means in each case being insertedand installed using correspondingly suitable robots in the manneralready described. It is not shown here that, in addition, it is alsopossible to insert spreadable or expandable plastic or steel rings whichare then expediently covered by subsequently inserted part-liners of thetype described. These additional supports are necessary, for example,when particularly heavy cables or high-tensile strength elements areused.

Although various minor modifications may be suggested by those versed inthe art, it should be understood that we wish to embody within the scopeof the patent granted hereon all such modifications as reasonably andproperly come within the scope of our contribution to the art.

We claim:
 1. A method for securing cables or elongate hollow sections ina system of ducts and pipes for flowing media, such as gas, waste water,rain water and mixed water, said method comprising the steps oftensioning at least one high-tensile-strength element between accessiblelocations within the system, and securing a cable to the element bysecuring means.
 2. A method for securing cables or elongate hollowsections in a system of pipes and ducts for flowing media, such as gas,waste water, rain water and mixed water, said method comprising thesteps of providing a cable having an elongate hollow section with atleast one high-tensile-strength element, and tensioning thehigh-tensile-strength element of the cable between accessible locationswithin the system.
 3. A method according to claim 2, wherein the cableis introduced into the system, said method including attaching anchoringelements to accessible locations of the walls at each of the anchoringpoints, securing the anchoring elements on the cable, suspending oneanchoring element from an anchoring point, inserting a turnbuckle inseries with the anchoring element of the other anchoring point with theturnbuckle being suspended from this anchoring point, and tensioning theat least one high-tensile-strength element by means of the turnbuckle.4. A method according to claim 1, wherein clamps, clips or eyes are usedas the securing means for the cable.
 5. A method according to claim 1,wherein anchoring coils made of stainless steel orglass-fiber-reinforced plastic are used as the securing means.
 6. Amethod according to claim 1, wherein the accessible locations are entryshafts of the system and the method includes arranging anchoring pointsfor the high-tensile-strength elements in the entry shafts of thesystem.
 7. A method according to claim 1, wherein deflection retainersare arranged as bends and branches in the system.
 8. A method accordingto claim 1, wherein a corrosion-resistant supporting cable with orwithout a protective encapsulation is used as the high-tensile-strengthelement.
 9. A method according to claim 1, wherein a dielectric cable isused as the high-tensile-strength element.
 10. A method according toclaim 2, wherein the cable has an elongate hollow section on which atleast one high-tensile-strength element with an encapsulation isarranged longitudinally and in an adhering manner on the cable sheath orthe hollow section, the high-tensile-strength element beinginjection-molded or co-extruded on the cable sheath or hollow sectionwith the same material encapsulation.
 11. A method according to claim 2,wherein a microcable is used, comprising a tube and optical waveguidesintroduced loosely therein.
 12. A method according to claim 2, wherein ahollow section with an initially empty longitudinal cavity is used, andin that optical waveguides or copper conductors are subsequentlyintroduced, as required, into the cavity.
 13. A method according toclaim 12, wherein a hollow section having a round cross section is used.14. A method according to claim 12, wherein a hollow section having aplanar or oval cross section is used.
 15. A method according to claim 1,wherein a cable having optical waveguides for the transmission ofoptical information is used.
 16. A method according to claim 1, whereina cable having electrical conductors for the transmission of electricalinformation is used.
 17. A method according to claim 1, wherein a cablehaving optical waveguides and electrical conductors is used.
 18. Amethod according to claim 2, wherein, the high-tensile-strength elementsare electrically conductive and electrical information and/or electricalpower are transmitted therealong.
 19. A method according to claim 1,which includes inserting at least one contact-pressure means in theregion between two anchoring points within the system, and pressing thehigh-tensile-strength element with an attached cable against the innerwall of a duct of the system by means of expansion of thecontact-pressure means.
 20. A method according to claim 19, wherein apart-liner made of a glass-fiber-reinforced plastic hose, which iscoated with an adhesive or impregnated through, is used as thecontact-pressure means.
 21. A method according to claim 19, wherein anexpandable or spreadable plastic or steel ring is used as thecontact-pressure means.
 22. A method according to claim 19, wherein thesteel ring is expanded by being spread open by a spreading spring.
 23. Amethod according to claim 19, wherein the contact-pressure means isdrawn onto an inflatable sac to form a combined arrangement,transporting the combined arrangement to the application site in theduct of the system between two anchoring points, inflating the sac topress the contact-pressure means against the wall to hold thehigh-tensile-strength element with attached cable thereagainst.
 24. Amethod according to claim 23, which includes curing the adhesive thenremoving the sac.
 25. A method according to claim 19, wherein acombination of part-liner and steel ring is used as the contact-pressuremeans.